In railroad industry, there have been desires for automatic pneumatic-electric coupling devices for a long time because of the concern for the safety of crewmen when it is necessary to manually couple train hoses. The prior art discloses numerous methods and apparatus for connecting brake lines of a train, such as U.S. Pat. No. 4,015,720 to Peche, U.S. Pat. No. 4,703,862 to Werner, U.S. Pat. No. 4,301,932 to Altherr, U.S. Pat. No. 4,071,148 to Tibbs, U.S. Pat. No. 3,802,578 to Farnworth, U.S. Pat. No. 3,854,597 to McClure et al., and U.S. Pat. No. 3,552,580 to Cope. However, it is not provided in the prior art designs any simple and effective means to automatically seal the juncture area of the coupling. When a rail-car is detached from a train or when train brake-in-two occurs, it is essential that the corresponding juncture areas of the two cars' brake lines common to each other also be disconnected, and in the meantime, air pressure at the compressor source is not lost. However, few of the prior art designs provide appropriate automatic hose-end sealing mechanisms for maintaining air pressure at the compressor source when train brake-in-two occurs. In addition, electric coupling features are not included in the prior art designs because of the difficulties of maintaining perfect electric contact in such an environment.